The ftavonoid pigments, one of the most numerous and widespread groups of natural constituents, are ofimportance and interest to a wide variety ofphysical and biological scientists and work on their chemistry, occurrence, natural distribution and biological function continues unabated. In 1975, a mono graph covering their chemistry and biochemistry was published by Chapman and Hall under our editors hip entitled The Flavonoids. The considerable success of this publication indicated that it filled an important place in the scientific literature with its comprehensive coverage of these fascinating and versatile plant substances. The present volume is intended to update that earlier work and provide a detailed review of progress in the ftavonoid field during the years 1975 to 1980. Although cross references are made to The Flavonoids, this supplement is entirely self-contained and where necessary, tabular da ta from the earlier volume are incJuded and expanded here. The choice oftopics in Recent Advances has been dictated by the developments that have occurred in ftavonoid research since 1975, so that not all subjects covered in The Flavonoids are reviewed again here. A major advance in ftavonoid separation has been the app1ication ofhigh performance liquid chromatography (HPLC) and this is reviewed inter alia in the opening chapter on separation techniques. An equally important development in the spectral analysis of ftavonoids has been the measurement of carbon-13 NMR spectra and this subject is authoritatively discussed in Chapter 2 and is also illustrated with the spectra of 125 representative ftavonoids.